1. Field of the Invention
This invention relates to storage container closures, and more particularly to an improved closure for a container having a generally cylindrical throat opening and a seal member which may selectively be placed loosely in the throat opening upon a first ledge or tightly upon a second ledge.
2. Description of the Prior Art
Circumstances may arise where a sealable container is needed for medium-term or long-term storage of articles or substances, yet it is desirable for the container to be easily openable for frequent or repetitive access to its contents. One common instance is the use of an ice bucket to store or transport ice cubes followed or preceded by use of the same bucket for dispensing ice at a social gathering such as a party or picnic. While a firm, positive seal of the bucket is desirable during transport and storage, a loose, easily opened closure of the bucket is preferred during the frequent access to the ice at the gathering.
Storage containers heretofore available have been provided with closures intended for either tight sealing or loose covering, but not both. Although it may be possible to loosely cover a container with a lid intended for tight sealing, typically no means are provided maintaining the lid in a proper orientation and relationship with the container, e.g., the lid may rest skewed and leave gaps or may bind or become stuck. Similarly, containers provided with closures intended for loose covering are typically not provided with means for obtaining a tight seal using the same parts.
U.S. Pat. No. 3,756,480, which is incorporated herein by reference, discloses a three-part press type seal comprising a locally distortable closure member contractably and distensibly constructed and having an elastic memory such that it is adapted to hermietically seal an open-mouthed container. The seal has a peripheral bead which may be contracted from a first diameter to a second smaller diameter by depressing a plunger which distorts a seal member formed integrally with the bead. Also disclosed is the use of such a seal to tightly close a container having a generally circular throat with a cylindrical wall and an annular ledge below the wall which are sealingly engaged by the seal bead.
Accordingly, there is a need for a container closure adapted for two modes of closing, a first in which the closure member rests loosely upon the container and is easily removed or replaced, yet which provides a uniform closing of the container, and a second in which the closure member tightly seals the container. Furthermore, it is desirable for such a closure to have insulative properties when used in a container with hot or cold contents.